Art of laundering and cleaning



Patented May 13, 1941 ART OF LAUNDERING AND CLEANING Howard B. Bishop, Summit, N. J., assignor, by mesne assignments, to The Pennsylvania Salt Manufacturing Company, Philadelphia, Pa.,

corporation of Pennsylvania No Drawing. Application June 25, 1937, Serial No. 150,266

8 Claims.

The invention relates to an industrial laundry method and particularly to methods and means.

for accomplishing improvements in the souring stage whereby desirable properties are developed with respect to the physical character of the laundered goods such as a soft finish or feel, a non-sticky, non-irritating surface, absence of bleeding, an increased brilliancy of colors, a deodorant effect of freshness and an absence of a tendency in the'goods to rolling when they are put on a fiat-work ironer.

In the conventional laundry practice the fab,- rics are first washed with soap to remove soiling. In this treatment the soap is so intimately associated with the fabrics being laundered that it is almost impossible to remove all of it by merely rinsing in clear water. Soap is a mild alkali and it often causes irritation of the skin if not neutralized. It is therefore the common practice in all commercial laundries to add to the rinse water a substance having an acid reaction. A vast number of materials have been tried out for this purpose.

The particular material which I employ and which has not heretofore been used in any laundering or cleansing operation is zinc silico fluoride. Such zinc silico fluoride when added to the last rinse of the laundry process in the proportion of approximately of 1% in water has the property of combining with the sodium stearate and other soluble soaps left in the fabrics from the antecedent soap treatment, forming combinations of which zinc stearate may be set forth as typical, and sodium silico fluoride. The sodium silico fluoride in turn reacts with the alkali in the goods to form sodium fluoride and silica. Zinc stearate is a preventive of irritation and apparently counteracts irritating effects which would otherwise result from the presence of fluorides. The result of the rinsing treatment described is that the zinc silico fluoride provides a powerful, nonirritating sour of extreme solubility which can be used successfully for souring colored work, preventing bleeding of the colors and making them more brilliant. It likewise gives the goods a soft, glove-silk finish.

The specific product which it is preferred to use is zinc silico fluoride crystallized in a vacuum crystallizer. The product is dried in a low temperature air dryer and the particles are about the size of granulated sugar so that it has quick solubility when used in the laundry wheel. The finished product will test about 98% to 99% zinc silico fluoride, the impurity being silica and zinc fluoride.

In the laundry practice contemplated by the present invention, the zinc silico fluoride is put use of any other sour.

into the last rinse of the laundry process. The small amount which remains in the goods after extracting is not detrimental and it is in fact preferable to leave it in the goods so that at the end of the laundry process they are on the acid side.

The effects of the use of zinc silico fluoride are various. It results in imparting a soft, smooth finish to silks such as cannot be obtained by the It results further in imparting brilliant, clear-cut colors on colored work instead of a somewhat muddy look which follows from. the use of other sours. There are quick penetration and complete souring in cold water because the zinc silico fluoride is so extremely soluble. There is a deodorant effect of freshness. Many women do not like laundry-washed silks or laundry-washed dark colors as the laundered goods are so harsh and/0r possess an unpleasant odor. There is nothing of this character in the laundered products when zinc silico fluoride is used as the souring agent.

An'important circumstance is that the beneficial qualities of the zinc silico fluoride are preserved even though other souring material is used in connection therewith. For example, ammonium silico fluoride which, when used alone, causes the goods to roll and not to follow through in the fiat-work ironer, can be used in association with zinc silico fluoride and the difliculty will thereby be corrected. Experiments have shown that the use of these two materials up to equal proportions, 50:50, has produced satisfactory results. The neutralizing value of zinc silico fluoride approaches that of ammonium silico fluoride.

The precise amount of zinc silico fluoride to be used in the last rinse of the laundry process depends, of course, on the degree of alkalinity or acidity of the water of the locality where the laundry process is executed and on the amount of alkali and soap left in the goods after the last water rinse following the soap treatment. Generally. however, the stated amount of approximately of 1% in the Water solution will suffice.

In my experiments with the nature ond character of results obtainable by the use of zinc silico fluoride solution, I discovered that if the clothes, after the customary suds bath and after a few rinses to remove most of the soap, are rinsed with a compound of fluorine having an acid reaction,

the pH of the solution being 4.0 or less (preferably 3.5 to 3.8) and having an element in the compound capable of combining with the stearic acid of the soap, there is formed an insoluble, nonsticky precipitate during the course of the rinsing procedure (which takes from five to ten minutes), the low pH being conducive also to the destruction of baceteria. The preferred compound for the stated purpose is zinc silico fluoride, which is to be distinguished from the sodium and ammonium silico fluorides which have heretofore been and are still being Widely used as souring agents in laundry practice. These last-named compounds, when used in the concentration contemplated by me for the rinsing treatment with zinc silico fluoride, are apt to produce irritating effects and to cause rolling of the goods on the flatwork ironer and to impart a harsh feeling to the fabric after drying, phenomena which do not occur when zinc silico fluoride is used. The preferred concentration of the rinsing bath of zinc silico fluoride should be such that, after reacting with the alkali and soaps present, the pH is less than 4.0.

The use of zinc silico fluoride entirely overcomes the rolling difliculty and, in addition, causes the goods to acquire the soft finish previously referred to.

I claim:

1. A laundry souring composition containing at least 50% of zinc silico fluoride and in the balance of the composition ammonium silico fluoride, the two fluorides being adapted to form a solution having a pH of 4 or less and to leave the goods on the acid side, the zinc silico fluoride in the solution being present in sufficient proportion to form an insoluble zinc soap with the soap residues.

2. The process of laundering goods, which comprises subjecting the goods to the usual soap treatment and to subsequent rinses to remove the major part of the soap but retaining some soap in the goods, thereupon subjecting the goods to the action of a solution, whose pH is 4 or less, of zinc silico fluoride adapted to impart an acid condition to the fabrics while fomiing an antiirritant, insoluble, non-sticky precipitate with the soapy material in the goods, and concluding the laundering process by separating the goods from said solution, whereby the goods at the conclusion of the laundering process are left on the acid side.

3. In the process of laundering goods, the step which comprises subjecting the goods after the soap treatment to the action of a solution containing zinc silico fluoride having a pH value of 4.0 or less to form in the goods an insoluble zinc soap and leaving the laundered goods on the acid side.

4. In the process of laundering clothes and the like after washing to remove soiling, the step which comprises rinsing the same in a solution containing zinc silico fluoride, retaining the clothing or the like in said solution for a suflicient length of time to make the colors more brilliant and to avoid bleeding thereof, and imparting a soft, non-sticky character to the same.

5. A rinse for use in the laundering of clothing and the like after washing to remove foreign matter, adapted to prevent bleeding of the colors contained in said clothing or the like and to render said colors more brilliant, to provide a soft finish to the same and to prevent the rolling of the clothing or the like during ironing, said rinse containing zinc silico fluoride.

6. The process of laundering fabrics which consists in subjecting fabrics to a soap treatment for the removal of soiling, separating the soiling and the major part of the soap from the fabrics but retaining some soap distributed in said fabrics and at the end of said treatment exposing said fabrics to a solution which is on the acid side and has zinc silico fluoride in solution in sufilcient amount to form with the retained soap an insoluble zinc soap, to cause such zinc soap to cling to the fibres as an insoluble precipitate and to render the fabrics acid, and concluding the laundering process by separating the fabrics from said solution.

'7. In the process of laundering goods, the step which comprises subjecting the goods after the soap treatment to the action of a solution containing zinc silico fluoride having a pH value of such magnitude in the acid range as to form in the goods an isoluble zinc soap and to leave the laundered goods on the acid side.

8. A laundry souring composition containing at least 50% zinc silico fluoride and in the balance of the composition ammonium silico fluoride, the two fluorides being adapted to form a solution having a pH of such magnitude as to leave the goods on the acid side, while the zinc silico fluoride is present in the solution in at least suificient proportion'to form an insoluble zinc soap with the soap residues.

HOWARD B. BISHOP. 

